S-91253A139 5-40 x 1 1/2" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional Durability: Crafted from black-oxide alloy steel with a Rockwell C39 hardness, providing superior resistance to wear and corrosion in harsh industrial environments.
• High Tensile Strength: Withstands up to 130,000 psi, ensuring reliable performance under heavy loads and reducing the risk of fastener failure.
• Precision Thread Fit: Class 3A thread fit and UNC coarse spacing offer excellent vibration resistance and easier, faster assembly in demanding applications.
• Secure Hex Drive: 5/64" hex drive allows for high-torque installation, minimizing cam-out and ensuring a tight, secure fit every time.
• Optimal Countersinking: Standard 82° flat head profile enables a flush finish, improving aesthetics and safety by eliminating protrusions.
• Full Thread Engagement: Fully threaded 1-1/2" length provides maximum grip and holding power across the entire fastener.
• Regulatory Compliance: Meets ASTM F835, RoHS 3, and REACH standards, guaranteeing material safety and performance reliability for global supply chains.

Professional Applications & Engineering Value

This 5-40 UNC flat head screw is engineered for high-stress applications where failure is not an option. The black-oxide alloy steel construction provides excellent corrosion resistance, extending service life in environments exposed to moisture and chemicals. The Class 3A thread fit with coarse UNC spacing ensures rapid assembly and superior vibration resistance, critical in machinery and automotive assemblies. The 82° countersink angle and flat head design allow for a seamless, flush mount, reducing aerodynamic drag in aerospace applications or preventing snagging in consumer products. With a fully threaded shank and high tensile strength, it delivers consistent clamping force, making it ideal for securing heavy-duty components in construction, industrial equipment, and electronics enclosures where reliability and durability are paramount.

Specification Summary & Compliance

This fastener features a 5-40 UNC thread size with Class 3A precision tolerance for optimal fit. It is fully threaded with coarse spacing and a right-hand thread direction. Manufacturing and material specifications comply with ASTM F835. The product is also confirmed to be RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring adherence to strict environmental and safety regulations for hazardous substances.